1. Field of the Invention
The present invention relates to a semiconductor device provided with an impurity layer having carriers formed through a low temperature process, and a method of manufacturing a semiconductor device which can form carriers in an impurity diffused layer in accordance with a low temperature process.
2. Description of the Prior Art
With the advance of the microminiaturization and higher integration of MOS integrated circuit elements, the areas of conduction portions for connecting metallic wires to polycrystalline silicon layers, gate electrodes, drain diffusion layers, etc. have become extremely smaller. With a result of this tendency, there arises a serious problem in that the contact resistance of the wiring increases more and more.
The contact resistance per unit area is determined by the difference in work function between the metal and the semiconductor and further by the concentration of impurity ions electrically activated in the semiconductor substrate. In order to reduce the contact resistance, it is preferable to decrease the difference in work functions between the metal and the semiconductor and to increase the impurity ion concentration of the semiconductor. Therefore, as a method of increasing the concentration of impurity ions electrically activated in the semiconductor, there has been so far known the method of forming an activated impurity layer by annealing at a high temperature a semiconductor substrate into which impurity ions have been implanted.
However, in the above-mentioned prior art method of implanting impurity ions into a semiconductor substrate and then annealing the semiconductor substrate at a high temperature so that the impurity ions can function as donors or acceptors, it has been impossible to increase the activated impurity ion concentration beyond the solid solution limit determined at the annealing temperature. Accordingly, since the impurity ions diffuse deeper and deeper during the high temperature treatment, there exists a problem in that the impurity atom concentration is reduced and the junction-depth of the diffused layer becomes deep.